Dark Horse programmer--c Language Foundation---pointers

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One, the pointer variable definition 1. The format of the definition

L Class name identifier * pointer variable name ;

l int *p;

2. Define the Post assignment first

L Simple Value

int a = 10;

int *p;

p = &a;

printf ("%d", *p);

L Simple Change value

*p = 9;

3. Assigning values at the same time as defined

int a = 10;

int *p = &a;

4. Implement modify argument 5. Watch out.

l int *p; p = 1000;

l int *p; *p = 100;

l int *p; *p = &a;

L%p The address value stored in the output pointer

L Other pointer type description, such as float *p; char *p;

L can not use the type, such as int a = 10; float *p = &a;

6. Clear the pointer

L p = 0;

L p = NULL;

Second, pointers and Arrays 1. Pointer to a one-dimensional array element 2. Traversing one-dimensional array elements with pointers

L Iterate through the char array (' i ', ' t '), and then iterate through the array of int types

the difference between L * (p+i) and * (p++)

L a+i and a++

L p[0],p[1]

Third, pointer and string 1. String review

Char s[] = "Jake";

2. Other ways to define strings

Char *s = "Jake";

Or

Char *s;

s = "Jake";

3. The difference between the two ways of definition

L Memory Analysis

L Drawing Analysis

L The difference between a constant and a variable string

L Constant Memory address view

Iv. functions that return pointers

The pointer is also a data type in C, so the return value of a function can certainly be a pointer-type

L The general form of a function that returns a pointer is: type name * Function name ( parameter list )

V. Pointer to function 1. Why can pointers point to a function?

function as a program, in memory also occupy a portion of storage space, it also has a starting address, that is, the entry address of the function. function has its own address, that's good, our pointer variable is used to store the address. Therefore, a pointer can be used to point to a function. Where the function name represents the address of the function.

2. Definition of pointers to functions

General form of definition: The return value type of the function (* pointer variable name ) ( parameter 1, parameter 2, ...);

3. Use note

L because this type of pointer variable stores the entry address of a function, it makes no sense to add or subtract them (such as p++)

The pointer variable that points to a function has two main uses:

· Calling functions

· Passing functions as arguments between functions

Dark Horse programmer--c Language Foundation---pointers